As a constituent for reducing blood glucose level increase, there have been known an extract from Gymnema Sylvestre leaves (JP Tokkai S64-85058, JP Tokkai H2-79955), an extract from Gymnema Inodrum (JP Tokkai H5-252897), and an extract from Gymnema Chingen (JP Tokkai H6-245735). They are considered to reduce blood glucose level increase because of an effect of reducing glucose absorption. Triterpene glycoside (JP Tokkai H6-128161) contained in Gymnema Inodrum is also reported to have the effect of reducing glucose absorption.
Monoterpene glycoside is known to have an effect of reducing blood glucose level increase through a sucrase inhibition effect (JP Tokkai H6-100453). Examples of such monoterpene glycoside include a betaine from a sugar beet (JP Tokkai H8-133970), a saponin mixture from Alaria elata (JP Tokkai H8-283169), and an α-glucosidase inhibitor (JP Tokkai H8-289783).
Additionally, there has been recently reported carbohydrate having an effect of reducing blood glucose level increase. Indigestible dextrin is known to show an effect of reducing blood glucose level increase after food intake for a person with easily rising blood glucose level (Kenko/Eiyosyokuhin Kenkyu, Vol. 2, No. 1, 52-56 (1999)), and to have an influence on fat metabolism (Kenko/Eiyosyokuhin Kenkyu, Vol. 3, No. 3, 47-58 (2000)). L-arabinose is also demonstrated to inhibit specifically the activity of small intestine sucrase which decomposes sucrose (Nihon Eiyo/Syokuryo Gakkai Shi (The Journal of JSNFS), Vol. 50, No. 2, 133-137 (1997)).
Although not carbohydrate, a hot water extract from Guava leaves, a plant extract, is known to inhibit the activities of carbohydrate degrading enzymes, such as maltase, sucrase and α-amylase. It is also known that its inhibition effect is particularly stronger for α-amylase than for the other two enzymes. Hence, it is demonstrated to reduce blood glucose level increase after food intake (Nippon NogeiKagaku Kaishi, Vol. 72, No. 8, 923-931 (1998)).